My Application model object contains a date field (time stamp):
#Entity
#Table(name = "MYTABLE")
public class Application {
private Date timeStamp;
...
}
I'm trying to construct a JPQL query that would select all applications that were changed today (i.e. their time stamp was changed anytime today). What is the best way to do this?
There is no perfect way with standard JPQL, JPQL doesn't provide Date arithmetic functions. But your provider might provide extensions (e.g. Hibernate and EclipseLink do). Or use a native SQL.
Related
I'm trying to use the jOOQ fetchInto() method to map to an existing Hibernate model Organization (class and its inheritances are below).
Organization organization = jooq().select().from(ORGANIZATION).fetchOne().into(Organization.class);
The problem I have is that I can't really understand what happens in DefaultRecordMapper as I feel I'm not entirely familiar with all the terms that are used. I'm trying to figure out how it applies to the Hibernate classes that are in my codebase.
So far what I've tried:
Use the jOOQ generated POJO's to see if it retrieves and maps the data at all (works).
Add a constructor, getters and setters to the Organization Hibernate model.
Add #Column annotation to name in the Organization Hibernate model.
What works:
id field gets mapped correctly.
What doesn't work:
name field doesn't get mapped (null).
createdAt and modifiedAt fields do not get mapped (null).
My question is: Is there something I am overlooking with the mapping and what are the things I should look at concerning the classes, fields, constructors and annotations with Hibernate models? I want to eventually map all the Hibernate models in the codebase and use fetchInto to do that.
Thanks! :)
#Entity
public class Organization extends BaseModel {
#Required public String name;
//... a lot of other code
}
#MappedSuperclass
public class BaseModel extends Model {
/** The datetime this entity was first saved. Automatically set by a JPA prePersist */
#NoBinding
#Column
#Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
public DateTime createdAt;
/** The datetime this entity was last modified. Automatically set by a JPA preUpdate */
#NoBinding
#Column
#Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
public DateTime modifiedAt;
//...
}
#MappedSuperclass
public class Model extends GenericModel { // Both Model and GenericModel are from the Play Framework
#Id
#GeneratedValue
public Long id;
public Model() {
}
public Long getId() {
return this.id;
}
public Object _key() {
return this.getId();
}
}
jOOQ doesn't support all the many JPA and Hibernate specific annotations. Historically, it supported a few JPA annotations (because why not), but full interop would be excessive and investing product development time in the wrong places. jOOQ is by no means a JPA implementation.
Step 0: Why didn't (some) of the mappings work?
As mentioned before, not all JPA specification is implemented. For example, a known issue is that #Column annotations are still mandatory in jOOQ:
https://github.com/jOOQ/jOOQ/issues/4586
There might be other such limitations, which could be considered bugs. Feel free to report them if you want to continue down this path: https://github.com/jOOQ/jOOQ/issues/new/choose
But things like #MappedSuperclass or #Type are unlikely to ever be supported by jOOQ.
Step 1: Do you really need it?
You've decided to create and run your query with jOOQ. I imagine your actual query is much more complex than what you're showing, because for that particular query, you don't need jOOQ.
Do you really need to map to Hibernate entities? Because even when you use Hibernate, the recommended approach is to use entities only when you're going to modify them and store the delta back to the database. If that's the case, see step 2 below. If it's not the case, why not use jOOQ's own mapping functionality to work with any style of jOOQ supported POJO?
Step 2: Use Hibernate to execute the jOOQ query
If you're using jOOQ only to build a rather complex SQL query and you need Hibernate entities as a result, then use Hibernate to execute the jOOQ query as documented here. A small utility should be enough:
public static <E> List<E> nativeQuery(EntityManager em, org.jooq.Query query, Class<E> type) {
Query result = em.createNativeQuery(query.getSQL(), type);
List<Object> values = query.getBindValues();
for (int i = 0; i < values.size(); i++)
result.setParameter(i + 1, values.get(i));
return result.getResultList();
}
I have a Spring Boot application running using JPA and Hibernate to automagically manage my entities. When I created this application, I used an older version of JPA that didn't have support for Java 8 DateTime API. However, without a lot of knowledge about JPA, I used LocalDateTime in my entities and it worked! Not having to know about the underlying database structure was great!
Until now...
I am upgrading JPA to a version that does support LocalDateTime, and I am facing an error with the way JPA is using this field. It used to save this object as a VARBINARY (tinyblob) field in my MySQL database, but now it is smart and expects it to be a TIMESTAMP type. Which means that when I start my application using the configuration spring.jpa.hibernate.ddl-auto=validate I get the error:
...
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException:
Schema-validation: wrong column type encountered in column [answer_time] in table [user_answer];
found [tinyblob (Types#VARBINARY)], but expecting [datetime (Types#TIMESTAMP)]
So now I am kinda lost on how to convert these fields to their new timestamp types. I was thinking about using FlyWay to write a migration script, but I have no idea how JPA stored the object as blob. When print a VARBINARY field as string this is what it looks like:
’ sr
java.time.Ser]º"H² xpw ã
!;:;Ö#x
This is how my entity looks like (which was unchanged during the upgrade):
#Entity
#Table(name = "user_answer")
public class UserAnswer {
private Long id;
private LocalDateTime answerTime;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public LocalDateTime getAnswerTime() {
return answerTime;
}
public void setAnswerTime(LocalDateTime answerTime) {
this.answerTime = answerTime;
}
}
How can I update my database so it converts the old VARBINARY fields that it used to store LocalDateTime data to TIMESTAMP fields?
What I would try (after backing up the DB!) :
Keep the old JPA API + implementation (Hibernate) versions.
Keep the old LocalDateTime field.
Add another java.sql.Date field to your entity. Make sure to annotate it properly etc. so that Hibernate knows exactly how the column should be defined.
For all entities:
Load each entity, read the LocalDateTime, convert and store it to the DateTime field, merge().
Remove the DateTime field.
Remove the column for the old LocalDateTime from the table.
Change the type of the DateTime field to LocalDateTime.
Upgrade the JPA API + implementation (Hibernate) versions.
JPA impl (Hibernate?) should store the DateTime as TIMESTAMP.
The JDBC driver should be able to pick up the TIMESTAMP into LocalDateTime.
Also, consider ZonedDateTime rather than LocalDateTime.
I'd like to add support for the Java 8 Date/Time API (JSR-310) in my JPA-enabled application.
It's clear that JPA 2.1 does not support the Java 8 Date/Time API.
As a workaround, the most common advise is to use an AttributeConverter.
In my existing application, I changed my entities to use LocalDate/LocalDateTime types for the column mapping fields and added legacy setter/getters for java.util.Date to them.
I created corresponding AttributeConverter classes.
My application does now fail when using Query.setParameter() with java.util.Date instances (it worked before the transition to the new API). It seems that JPA expects the new date types and does not convert it on the fly.
I expected that if passing an argument to setParameter() of a type for which an AttributeConverter has been registered, it would be automatically converted by the converter.
But this seems to be not the case, at least not using EclipseLink 2.6.2:
java.lang.IllegalArgumentException: You have attempted to set a value of type class java.util.Date for parameter closeDate with expected type of class java.time.LocalDate from query string SELECT obj FROM [...]
at org.eclipse.persistence.internal.jpa.QueryImpl.setParameterInternal(QueryImpl.java:937) ~[eclipselink-2.6.2.jar:2.6.2.v20151217-774c696]
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.setParameter(EJBQueryImpl.java:593) ~[eclipselink-2.6.2.jar:2.6.2.v20151217-774c696]
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.setParameter(EJBQueryImpl.java:1) ~[eclipselink-2.6.2.jar:2.6.2.v20151217-774c696]
[...]
Questions:
Is this behavior expected? Did I miss something?
Is there a way to use the new date types as fields without breaking existing code?
How did you deal with the transition to the new Date/Time API within JPA?
UPDATE:
However, It seems that at least using EclipseLink, custom types for which an AttributeConverter exists, are not fully supported:
Within JPQL queries, neither the actual field type nor the converted database type can be used as a parameter.
When using the converted database type, the exception described above occurs.
When using the actual field type (e.g. LocalDate), it's directly passed to the jdbc driver which doesn't know this type:
Caused by: java.sql.SQLException: Invalid column type
at oracle.jdbc.driver.OraclePreparedStatement.setObjectCritical(OraclePreparedStatement.java:10495)
at oracle.jdbc.driver.OraclePreparedStatement.setObjectInternal(OraclePreparedStatement.java:9974)
at oracle.jdbc.driver.OraclePreparedStatement.setObjectInternal(OraclePreparedStatement.java:10799)
at oracle.jdbc.driver.OraclePreparedStatement.setObject(OraclePreparedStatement.java:10776)
at oracle.jdbc.driver.OraclePreparedStatementWrapper.setObject(OraclePreparedStatementWrapper.java:241)
at org.eclipse.persistence.internal.databaseaccess.DatabasePlatform.setParameterValueInDatabaseCall(DatabasePlatform.java:2506)
I would expect that EclipseLink converts the field type to the java.sql type using the AttributeConverter.
(see also this bug report: https://bugs.eclipse.org/bugs/show_bug.cgi?id=494999 )
Which leads us to the most important question #4:
Is there a workaround/solution to support java 8 date fields using EclipseLink, including the possibility to use a query parameters on such a field?
ADDITIONAL INFO
AttributeConverter used (for LocalDateTime conversion)
Additional information to reproduce exception
Some time ago, I converted a Java EE 7 web app from Java 7 to Java 8, and replaced java.util.Date in entities with LocalDate and LocalDateTime.
Yes, that behavior is expected, because an AttributeConverter only converts between the type used for entity fields and the database type (ie, java.sql.Date, etc.); it does not convert between an entity field type and a java.util.Date used in a query parameter.
As far as I know, no, there is no way to continue using java.util.Date in existing code, after introducing the java.time types into JPA entities.
Besides creating the necessary AttributeConverter implementations, I changed all occurrences of java.util.Date to the appropriate java.time types, not only in entities but also in JPA-QL queries and in business methods.
For item 2, of course you can go some way by using utility methods and getters/setters that convert between java.util and java.time, but it's not going to go all the way. More importantly, I don't quite see the point of introducing java.time types into JPA entity attributes, if you are not willing to convert the remaining code that uses these
attributes. After the conversion work I did in that Java EE app, there were no uses of java.util.Date left anywhere (though I also had to create converters for JSF).
With so many bugs in the provider itself I don't think you have much choice but to use java.util.Date on the mapping level and java 8 dates on the API level.
Assuming you write a utility class for conversion to/from java.util dates called DateUtils, you could define your mappings as follows:
#Entity
public class MyEntity {
#Column("DATE")
private Date date; // java.util.Date
public void setDate(LocalDateTime date) {
this.date = DateUtils.convertToDate(date);
}
public LocalDateTime getDate() {
return DateUtils.convertFromDate(date);
}
}
Then to filter by date in JPQL:
public List<MyEntity> readByDateGreaterThan(LocalDateTime date) {
Query query = em.createQuery("select e from MyEntity e where e.date > :date");
query.setParameter("date", DateTuils.convertToDate(date));
return query.getResultList();
}
So, java.util dates would be used in entities and DAOs (Repositories) internally, while the API exposed by entities and DAOs would take/return java 8 dates, thus enabling the rest of the application to operate with java 8 dates only.
I have the following setup:
EclipseLink v2.6.2
h2 Database v1.4.191
Java 8
The entity class is like:
#Entity
public class MeasuringPoint extends BaseEntity {
#Column(nullable = false)
private LocalDateTime when;
public void setWhen(LocalDateTime when) {
this.when = when;
}
public LocalDateTime getWhen() {
return when;
}
}
The required converter for JPA 2.1 is:
#Converter(autoApply = true)
public class LocalDateTimeConverter implements AttributeConverter<LocalDateTime, Timestamp> {
#Override
public Timestamp convertToDatabaseColumn(LocalDateTime attribute) {
return attribute == null ? null : Timestamp.valueOf(attribute);
}
#Override
public LocalDateTime convertToEntityAttribute(Timestamp dbData) {
return dbData == null ? null : dbData.toLocalDateTime();
}
}
Now I can make a query
List<?> result = em.createQuery(
"SELECT p FROM MeasuringPoint p WHERE p.when = :custDate")
.setParameter("custDate", LocalDateTime.now())
.getResultList();
and it works like a charm. The result contains the expected entities. The conversion to TIMESTAMP is done automatically. When you have queries using the Criteria API, have a look at this answer which shows how to use LocalDateTime within Criteria API queries.
I wonder why it doesn't work with your code. Maybe the H2 JDBC driver does support something your Oracle doesn't.
AttributeConverter is working as designed, as the converter is meant to handle the back and forth between your entity type and the database type. Validation is verifying the type of the parameter doesn't match the type within the entity - just because your attribute converter can handle it, doesn't mean it fits the contract of the attribute converter types. JPA only says it will go through the converter before going to the database, and in this case it doesn't go to the database.
If you don't like Rogério's suggestions, you can
1) modify the EclipseLink code to relax the validation to allow it to go through to your converter, or
2) change your attribute type to 'Object' instead so that all parameter types you may pass in will go to your converter.
i'm trying to convert a 'TableController'-Class we used (without ORM) to generate dynamic SQL (actually the order column and direction is appended to the SQL).
Think of this 'TableController' as a class that have a function to return a list of Entities of a given class (known at runtime), in a given order (String column/property name, boolean asc/desc, both at runtime).
The challenge is now, with JPA (Hibernate - but the customer requires to use JPA Interfaces only): How can i realize this without String concatenation, and in a type safe manner?
Thanks!
The challenge is now, with JPA (Hibernate - but the customer requires to use JPA Interfaces only): how can I realize this without String concatenation, and in a type safe manner?
If you're using a JPA 2.0 implementation, I think you should look at the Criteria API to build dynamic queries.
If you're using JPA 1.0, there is no standard way apart from String concatenation (and my suggestion would be to use Hibernate's proprietary Criteria Queries).
The following article might also give you some (concrete) ideas: Hibernate Querying 102 : Criteria API.
Imagine a method that has three parameters: Class entityClass, String orderByColumn, boolean ascending. How would i create a query without string concatenation that gives me all objects of the given class in the correct order?
With the Criteria API from JPA 2.0, you could do something like this:
public <T> List<T> findAllEntitiesOrderedBy(Class<T> entityClass, String orderByColumn, boolean ascending) {
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<T> criteria = builder.createQuery(entityClass);
Root<T> entityRoot = criteria.from(entityClass);
criteria.select(entityRoot);
javax.persistence.criteria.Order order = ascending ? builder.asc(entityRoot.get(orderByColumn))
: builder.desc(entityRoot.get(orderByColumn));
criteria.orderBy(order);
return em.createQuery(criteria).getResultList();
}
I have project use EJB 3.0 and implement Toplink framework for model layer.
When using EJBQL to process data, I see it seems have some limitation:
It cannot process datatime such as find a part of date such as day, month or year
It cannot find datetime among from...to
It cannot comparison datetime field
It cannot map a class not entity to a customize native select query because I want to get List data from SELECT statement but when I query in case join 2 or more table and map the object output into a class but impossible
#PersistenceContext private
EntityManager em;
em.createNativeQuery("SELECT
a.usertype , b.username, b.userpass
FROM tablea a, tableb b WHERE a.id =
b.id,MyClass.class).getResultList
.....
class MyClass(){
String usertype;
String username;
String userpass;
}
Could you help me any ideas?
Thank in advance!
It can not, do it in your code. Otherwise, you need to use something database specific on one side of your condition.
It can, why not. You can use between :fromDate and :toDate in the query, or use > :fromDate and < :toDate, in the NamedQuery. Where is the problem.
It can. Similar to the last one, use = sign instead
It can using #SqlResultSetMapping. Refer to this.